Volcano-Curves for Dehydrogenation of 2-Propanol and Hydrogenation of Nitrobenzene by SiO2-Supported Metal Nanoparticles Catalysts As Described in Terms of a d-Band Model

To confirm whether the activity trends in multistep organic reactions can be understood in terms of the Hammer–Nørskov d-band model in combination with the linear energy relations, we studied correlations between the reaction rates for dehydrogenation and hydrogenation reactions and the position of the d-band center (ε d ) relative to the Fermi energy ( E F ), the ε d – E F value, of various metal catalysts. SiO 2 -supported metal (M = Ag, Cu, Pt, Ir, Pd, Rh, Ru, Ni, and Co) catalysts with the same metal loading (5 wt %) and similar metal particle size (8.9–11.7 nm) were prepared. The dehydrogenation of adsorbed 2-propanol in a flow of He and the hydrogenation of adsorbed nitrobenzene in a flow of H 2 were tested as model reactions of organic reactions on the metal surface. As a test reaction of H 2 dissociation on the surface, SiOH/SiOD exchange on the M/SiO 2 catalysts in a flow of D 2 is carried out. The liquid phase hydrogenation of nitrobenzene under 3.0 MPa of H 2 is adopted as an organic reaction under realistic conditions. Generally, the activities show volcano-type dependences on the ε d – E F value, indicating that the ε d – E F value is useful as a qualitative activity descriptor in heterogeneous catalysis of metal nanoparticles for multistep organic reactions.